The present invention relates to an apparatus for anchoring a tubular element such as a catheter within a passageway in a mammalian body. In particular, the present invention relates to an anchoring device provided within a catheter that is operable to position and retain the tubular element in place within vessels, arteries, ducts, and channels within the mammalian body.
In various medical procedures in which a catheter is inserted into tubular shaped structures in the body, such as vessels, arteries, ducts, and channels, it is important to anchor the catheter for specific periods of time at a selected location. For example, a common medical procedure that utilizes catheters involves the measuring of certain characteristics of a patient's blood and the monitoring of the patient's blood on a continuous basis. Continuous monitoring is desirable to obtain real time monitoring of the patient's condition. Typically, various intravascular blood gas sensing devices are used to measure blood gas concentrations, including concentrations of oxygen, carbon dioxide, pH level, and the like. However, a challenging problem in the use of blood gas sensors is the difficulty in retaining the catheter in place within the vessel and the difficulty in stabilizing the blood gas sensors so as to obtain an accurate flow reading. For example, due to movement of the sensors, attempts to measure blood gas concentrations directly and continuously have resulted in inaccurate and erratic sensor values.
In addition, the difficulty in anchoring or retaining tubular elements in place within a body passageway, such as a blood vessel, also affects their use with translumenal ultrasonic sensors which can be used to obtain images of blood vessels. For example, it is important to minimize the movement of translumenal ultrasonic sensors within a body passageway such as a blood vessel in order to obtain high quality images of the blood vessel. Moreover, the difficulty in anchoring or retaining tubular elements in place within a body passageway may also affect their use with drug delivery systems, drug dosing, ultrasound systems, and sampling of a body material or fluid.
Devices for positioning tubular elements such as catheters within the body are known. However, many of these devices are not designed to be reversibly removed or moved to another location, and many of these devices are not designed to position or anchor a catheter over a very short distance, i.e., less than 1 centimeter.
There are known devices for positioning a sensor device in an artery, as exemplified in U.S. Pat. No. 5,265,606 to Kujawski. The disclosed device includes an introducer catheter formed in a zigzag pattern having successive bends alternating on opposite sides of the central axis of the catheter, such that when the catheter is placed in the patient's artery, the bends on the opposite sides of the central axis will engage the wall of the artery lumen thus tending to stabilize the catheter in the lumen. However, the device is not designed to anchor the catheter over a very short distance, as the device includes a probe constructed to be passed through the catheter shaft, and the distal end of the probe protrudes substantially beyond the distal outlet. Moreover, in certain embodiments, the tip of the probe may be pointed which creates the danger of puncturing the vessel wall.
Other known devices, such as disclosed in U.S. Pat. No. 5,135,517 to McCoy, include at least two separate positioning elements comprised of shape memory alloys and used to position a core member within a passageway formed in a body. However, the device uses a power supply to activate the thermal shape memory metal. Use of a power supply increases the complexity and the cost. In addition, if the power supply in McCoy is turned off, the device does not necessarily contract back to its original shape by itself. Moreover, there is a danger of overheating the device, and there is the time inconvenience of having to wait for the device to cool down so that it can be safely removed from the body without injury to vessels.
Thus, there is a need for a device that anchors or positions a tubular element such as a catheter in body passageways, such as vessels, arteries, ducts, and channels. In particular, there is a need for a device that is designed to be reversibly removable from one selected location to another and that is designed to anchor or position a catheter over a very short distance, i.e., less than 1 centimeter, and that is designed to aid in accurately positioning a catheter in body passageways. In addition, there is a need for a device that anchors or positions a catheter in place within a body passageway and stabilizes intravascular blood gas sensors (O2, CO2, pH, and the like), so as to obtain accurate flow readings or sensor values. Moreover, there is a need for a device that anchors or positions a catheter in place within a body passageway and that minimizes the movement of translumenal ultrasonic sensors in the body passageway, so as to obtain high quality images of the body passageway such as blood vessels, etc., and that also minimizes movement of tubular components used in drug delivery systems, ultrasound systems, and body sampling systems. There is also a need for a device that may comprise a pseudoelastic shape memory alloy material and that includes all of the advantages that such a material provides. Finally, there is a need for a device that is easy to manufacture and assemble, that requires no power supply, requires no external heating or body heating or cooling down, and that minimizes the potential for tissue damage or discomfort to a patient upon insertion, deployment, and removal of the device.